How to Grow Heracleum Plants in your Garden

Gardener's HQ Guide to Growing Hogweed, Cow Parsnip, Cartwheel Flower, and Giant Masterwort

Members of the Heracleum genus are hardy perennials that reach great heights of between 2.5 and 5.5 metres (8 to 17 feet).

They carry small white or pink flowers in umbels atop thick stems. They are ideal plants to grow in a wild flower garden or close to water.

Some common names for Heracleum include Cow Parsnip, Giant Hogweed, Cartwheel flower and Masterwort.

Heracleum sphondylium
Heracleum sphondylium - Hog Weed by Mick E. Talbot.

Heracleum Growing and Care Guide

Common Names: Hogweed, Giant Hogweed, Cow Parsnip, American Cow Parsley, Cartwheel Flower, Giant Masterwort.
Life Cycle: Hardy perennial.
Height: 110 to 144 inches (280 to 365 cm).
Native: Central Asia.
Growing Region: Zones 3 to 9.

Flowers: Middle of summer.
Flower Details: White, pink. Umbels.
Foliage: Compound.

Sowing: 1/4 inch (6 mm). Germination time: one to three months.
Seed: Method 1: Seeds should first be sown into peat pots in the autumn. Next sink the pots into the ground in an area that offers shade, preferably close to a wall that faces north. Provide a glass/plastic covering. Keep an eye on the pots to ensure that the soil remains moist. Bring the pots indoor in spring. Transplant to the final location in autumn.
Seed: Method 2: In the spring, sow seeds in a peat pot, wrap in a plastic bag, then stratify by refrigeration for three weeks. Next bury the pots as described above. Once seedlings emerge remove the covering. Transplant them as above.

Requirements and care: Full sunlight or light shade. Rich soil, moist soil. Deadhead. Propagate: Self seeds readily; dividing in the spring or the autumn.

Miscellaneous: Invasive species in many areas especially parts of North America and Europe. Wear gloves as touching the Giant Hogweed plant may lead to Phytophotodermatiti resulting in skin rashes. The seeds of Persian Hogweed are used in powder form with beans in order to reduce flatulence.

How to Grow Cow Parsnip (Heracleum)

When growing Cow Parsnips outdoors they should be prepared in the spring or autumn.

Spring sowing of Cow Parsnips is discussed here. The seeds should be sown in peat pots at a depth of 6 mm (1/4 inch) then the pots put in a black plastic bag, and placed in the the fridge for three weeks.

The pots should then be transferred and sank into a shady part of the garden, cover with glass.

Let the seedlings that appear grow until the autumn. Transplant the young Heracleum seedlings into a sunny or partially part of the garden. This should have a rich and moist soil.

As they are large plants, Heracleum should be spaced at about 1 to 1.25 m (40 to 50 inches) apart.

Caring and control of Cow parsnips and other Heracleum Plant Species in the Garden

It is important to keep on top of Cow parsnips and other Heracleum Plants. They can spread rapidly and become invasive plants that will take over the garden given half a chance.

It is necessary to remove the flowering stems once they appear. Wear gloves when doing this as the leaves of the Heracleum plant are toxic, and may cause a skin rash. If you require more plants then they can be had by division, or just let them do their thing.

Common Questions

How many members does the Heracleum genus have?

The Heracleum genus comprises about 60 species, notable for their large size and distinct flowering structures.

Do members of Heracleum make a good garden or landscaping plant?

Some Heracleum species, such as Heracleum sphondylium or common hogweed, can make interesting additions to the garden but should be handled with care due to their sap.

Which Heracleum species are most frequently grown by gardeners?

Heracleum sphondylium is often grown, but its relative, the Giant Hogweed (Heracleum mantegazzianum), is notable for its massive size.

Are members of the Heracleum plant genus fragrant?

Many Heracleum species have a distinctive scent when their leaves or stems are crushed, but it is not generally considered fragrant.

What is the perfect location to grow Heracleum?

Heracleum species prefer full sun to part shade and moist, fertile soil.

Is Heracleum invasive in the USA, if so in which states?

The Giant Hogweed (Heracleum mantegazzianum) is considered invasive in many parts of the USA, especially the Northeast, Midwest, and Pacific Northwest.

How do I remove Heracleum plants from my garden?

Removing Heracleum should be done with caution due to its phototoxic sap. It's recommended to use professionals for this task.


The Heracleum genus, part of the Apiaceae family, is made up of biennial and perennial herbs known as hogweeds. Native to temperate regions of the Northern Hemisphere, they are identified by their large, umbel-shaped flower clusters. Notable species include Heracleum sphondylium and Heracleum mantegazzianum.

Heracleum prefers full sun to partial shade and moist, well-drained soil. The plants are robust and can tolerate a wide range of conditions. Propagation is generally by seeds, sown in late summer to early fall.

I hope that you enjoyed this guide on how to grow Heracleum plants. You may also enjoy my gardening guides on how to grow Narcissus, Veltheimia plant, and Ixia plants.